class Solution {
public:
    int dx[4]={0,0,1,-1};
    int dy[4]={1,-1,0,0};
    int m,n;
    bool vis[51][51];
    int maxAreaOfIsland(vector<vector<int>>& grid) {
         m=grid.size(); n=grid[0].size();
        int ret=0;
        for(int i=0;i<m;i++)
        {
            for(int j=0;j<n;j++)
            {
                if(grid[i][j]==1&&!vis[i][j])
                ret=max(ret,bfs(grid,i,j));   
            }
        }
        return ret;
    }
    int bfs(vector<vector<int>>& grid,int i,int j)
    {
        queue<pair<int,int>>q;
        int count=1;
        q.push({i,j});
        vis[i][j]=true;
        while(q.size())
        {
            auto [a,b]=q.front();
            q.pop();
            for(int k=0;k<4;k++)
            {
                int x=a+dx[k];
                int y=b+dy[k];
                if(x>=0&&x<m&&y>=0&&y<n&&grid[x][y]==1&&!vis[x][y])
                {
                    q.push({x,y});
                    vis[x][y]=true;
                    count++;
                }
            }
        }
        return count;
    }
};
